Prisoner of Azkaban grossed a total of $796.6 million worldwide,[1] with its box office performance ranking as the lowest-grossing in the series. However, it was, at the time, the best-reviewed film of the series. It is widely considered by critics and fans to be the best installment of the franchise.[2][3][4]

The Fat Lady's portrait, which guards the Gryffindor quarters, is found ruined and empty, and she is found in another painting where she tells Dumbledore that Sirius Black has entered the castle. During a stormy Quidditch match, dementors attack Harry, causing him to fall off his broomstick, which is then destroyed by the Whomping Willow. Lupin privately teaches Harry to defend himself against dementors, using the Patronus charm. At Hogsmeade, Harry is shocked to learn that Sirius is his godfather and was his parents' best friend. Sirius was accused of betraying the Potters' hiding location to Voldemort and murdering their mutual friend Peter Pettigrew.

Harry, Ron, and Hermione visit Hagrid to console him over Buckbeak's impending execution. Afterwards, Ron's pet rat Scabbers escapes, and when Ron gives chase, a large dog appears and drags both Ron and Scabbers into a hole at the Whomping Willow's base, which is actually an underground passage to the Shrieking Shack. The trio discovers that the dog is actually Sirius, who is an Animagus. Lupin arrives and embraces Sirius as an old friend, then admits to being a werewolf, and explains that Sirius is innocent. Much to Ron's surprise, Scabbers is actually Pettigrew, an Animagus who committed the crime for which Sirius was convicted. After forcing him back into a human, Lupin and Sirius prepare to kill Pettigrew, but Harry intervenes and convinces them to turn Pettigrew over to the Dementors.

As the group departs, the full moon rises; Lupin transforms into a werewolf, and while Sirius transforms as well and fights him off, Pettigrew escapes in his rat form. Sirius and Harry are attacked by dementors. Harry sees a figure save them by casting a powerful Patronus. He believes the mysterious figure is his dead father, and passes out, awakening to discover that Sirius has been captured and sentenced to the Dementor's Kiss. Acting on Dumbledore's advice, Harry and Hermione travel back in time, watching themselves repeat the night's events. They save Buckbeak from execution and witness the Dementors overpower Sirius and Harry. The present Harry realises that he himself was the one to cast the Patronus, not his father, and does so. Harry and Hermione then rescue Sirius, who escapes on Buckbeak. Lupin resigns to preempt an uproar from parents over a werewolf teaching their children. Sirius sends Harry a Firebolt broom, the fastest broom in the world, and Harry happily takes it for a ride.

Michael Gambon as Albus Dumbledore, the Hogwarts Headmaster. Gambon assumed the role after Richard Harris, who played Dumbledore in the previous two films, died on 25 October 2002.[5] Despite his illness, Harris was determined to film his part, telling a visiting David Heyman not to recast the role.[6] Four months after Harris's death, Cuarón chose Gambon as his replacement.[6][7] Gambon was unconcerned with bettering or copying Harris, instead giving his own interpretation, putting on a slight Irish accent for the role,[8] as well as completing his scenes in three weeks.[9] Rumours of Ian McKellen being offered the role started to spread, but when confronted, he turned the rumours down, stating that he has played a similar character in Gandalf of The Lord of the Rings trilogy. He also stated it would have been inappropriate to take Harris' role, as the late actor had called McKellen a "dreadful" actor.[10][11] Harris's family had expressed an interest in seeing Harris's close friend Peter O'Toole being chosen as his replacement.[12]

Gary Oldman as Sirius Black, an escapee from the Wizarding prison Azkaban and Harry's godfather. Oldman accepted the part because he needed the money, as he had not taken on any major work in several years, having decided to spend more time with his children.[13] He drew inspiration from Cuarón, whom he described as having "such enthusiasm and a joy for life,"[14] and compared Sirius to John Lennon.[13] He was "surprised by how difficult it was to pull off", comparing the role to Shakespearean dialogue.[14] Oldman suggested Sirius's hairstyle, while Cuarón designed his tattoos.[14] He had read the first book, and his children were fans of the series. The part made Oldman a hero with his children and their schoolmates.[8]

David Thewlis as Professor Lupin, the new Defence Against the Dark Arts teacher at Hogwarts. Thewlis, who had previously auditioned for the role of Quirrell in Harry Potter and the Philosopher's Stone, was Cuarón's first choice for the role of Professor Lupin. He accepted the role on advice from Ian Hart, the man who was cast as Quirrell, who told him that Professor Lupin was "the best part in the book."[15] Cuarón told Thewlis that he thought Lupin was gay, pitching him as a "gay junkie", although his idea turned out to be incorrect.[16] Thewlis had seen the first two films and had only read part of the first book, although after taking the role he read the third. He was excited about the prospect of making a children's film, and thoroughly enjoyed filming.[8]

With Prisoner of Azkaban, production of the Harry Potter films switched to an eighteen-month cycle, which producer David Heyman explained was "to give each [film] the time it required."[6]Chris Columbus, the director of the previous two films, decided not to return and helm the third instalment as he "hadn't seen [his] own kids for supper in the week for about two and a half years."[17] Even so, he remained on as a producer alongside Heyman.[18]Guillermo del Toro was approached to direct, but considered the film "so bright and happy and full of light, that [he] wasn't interested."[19]Marc Forster turned down the film because he had made Finding Neverland and did not want to direct child actors again. Warner Bros. then composed a three-name short list for Columbus's replacement, which comprised Callie Khouri, Kenneth Branagh (who played Gilderoy Lockhart in Chamber of Secrets) and eventual selection Alfonso Cuarón.[20] Cuarón was initially nervous about accepting as he had not read any of the books, or seen the films. After reading the series, he changed his mind and signed on to direct,[21] as he had immediately connected to the story.[18] Cuarón's appointment pleased J. K. Rowling who loved his film Y Tu Mamá También and was impressed with his adaptation of A Little Princess.[22] Heyman found that "tonally and stylistically, [Cuarón] was the perfect fit."[6] As his first exercise with the actors who portray the central trio, Cuarón assigned Radcliffe, Grint and Watson to write an autobiographical essay about their character, written in the first person, spanning birth to the discovery of the magical world, and including the character's emotional experience. Of Rupert Grint's essay, Cuarón recalls, "Rupert didn't deliver the essay. When I questioned why he didn't do it, he said, 'I'm Ron; Ron wouldn't do it.' So I said, 'Okay, you do understand your character.' That was the most important piece of acting work that we did on Prisoner of Azkaban, because it was very clear that everything they put in those essays was going to be the pillars they were going to hold on to for the rest of the process."[8][23]

Some sets for the film were built in Glen Coe, Scotland, near the Clachaig Inn. The indoor sets, including ones built for the previous two films, are mainly in Leavesden Film Studios. The Hogwarts Lake was filmed from Loch Shiel, Loch Eilt and Loch Morar in the Scottish Highlands. Incidentally, the train bridge, which was also featured in the Chamber of Secrets, is opposite Loch Shiel and was used to film the sequences when the Dementor boarded the train. A small section of the triple-decker bus scene, where it weaves in between traffic, was filmed in North London's Palmers Green. Some parts were also filmed in and around Borough Market and Lambeth Bridge in London.

Rowling allowed Cuarón to make minor changes to the book, on the condition that he stuck to the book's spirit.[21] She allowed him to place a sundial on Hogwarts' grounds, but rejected a graveyard, as that would play an important part in the then unreleased sixth book.[21] Rowling said she "got goosebumps" when she saw several moments in the film, as they inadvertently referred to events in the final two books, she stated "people are going to look back on the film and think that those were put in deliberately as clues."[22] When filming concluded, Cuarón found that it had "been the two sweetest years of my life," and expressed his interest in directing one of the sequels.[21]

Cuarón originally wanted to move away from CGI toward puppetry. He hired master underwater puppeteer Basil Twist to help, using puppets to study the potential movement of the Dementors.[6] Once it became apparent that puppetry would be too expensive and unable to portray the specific elements of the Dementors, Cuarón turned to CGI; however, he and his team did use footage of Dementor puppets underwater as a basis for the flowing movements of the computer-generated Dementors.

The Academy Award-nominated score was the third and final score in the series to be composed and conducted by John Williams. It was released on CD on 25 May 2004. In general, this film's music is not as bright as that of the previous films, with distinct medieval influences in the instrumentation. One of the new themes, "Double Trouble," was written during production so that a children's choir could perform it in Hogwarts's Great Hall in one of the film's earlier scenes. The lyrics of "Double Trouble" are from a ritual performed by the Weïrd Sisters in Act 4, Scene 1 of Shakespeare's Macbeth.[25] The film's trailer prominently features the cues "Anticipation" and "Progeny" by Brand X Music, a trailer music band.

Prisoner of Azkaban was, at the time of publication, the series' longest book. The increasing plot complexity necessitated a looser adaptation of the book's finer plot lines and back-story. The film opens with Harry using magic to light his wand in short bursts, whereas in the same scene in the book, he uses a flashlight, as performing magic outside the wizard world is illegal for wizards under the age of seventeen. Also in the book, there is no shrunken head in the Knight Bus, while in the film, a rude shrunken head talks through most of the Knight Bus scene. The connection between Harry's parents and the Marauder's Map is only briefly mentioned,[26] as is Remus Lupin's association to both the map and James Potter.[27] Additionally, it was never mentioned who the Marauders were or who the nicknames (Mooney, Wormtail, Padfoot, and Prongs) belonged to. Some exposition was removed for dramatic effect: both the Shrieking Shack and Scabbers the rat are mentioned only very briefly in the film, while they receive a more thorough coverage in the novel.[26] Most of Sirius Black's back story is also cut, with no mention of the manner of his escape from Azkaban.[27]

On account of pace and time considerations, the film glosses over detailed descriptions of magical education. Only one Hippogriff, Buckbeak, is seen, and only Malfoy and Harry are seen interacting with the Hippogriff during Care of Magical Creatures lessons, and most other lessons, including all of Snape'spotions classes, were cut from the film.[26] The Fidelius Charm's complicated description is removed entirely from the film, with no explanation given of exactly how Black "betrayed" the Potters to Lord Voldemort. Many of this scene's lines are redistributed amongst Cornelius Fudge and Minerva McGonagall; in compensation, McGonagall's exposition of the Animagus transformation is instead given by Snape.[26]

In the film, where Harry and Hermione have travelled back in time and are hiding outside of Hagrid's hut, it is heavily implied that Dumbledore somehow knows that they are there, as he distracts the other characters at key moments or slows down the proceedings (such as by suggesting that he sign Buckbeak's execution order as well, then after Fudge agrees he says it will take some time as he has an extremely long name), which allows Harry and Hermione time to free Buckbeak unseen. In the book, Dumbledore merely comments that the executioner must sign the order, right before he is about to leave the cabin to execute Buckbeak.

The embryonic romantic connection between Ron and Hermione is more prominent in the film than the book; in response to criticism of the first two films for sacrificing character development for mystery and adventure, the emotional development of all three lead characters is given more attention in the third film.[26] However, some critics and fans thought that the result was a murky plotline. That said, any mention of the beginnings of Harry's crush on Cho Chang is removed.[28] Harry's darker side is first glimpsed in this film, when Harry proclaims, "I hope he [Black] finds me. Because when he does, I'm going to be ready. When he does, I'm going to kill him!"[26] Also, Harry receives the Firebolt at the film's end, while in the book he receives it anonymously at Christmas and it is confiscated for a few weeks to be checked for possible jinxes by Professor Flitwick and Madam Hooch. Lastly, in relation to the change in the arrival of the Firebolt, one of the two Quidditch matches featured in the book (between Gryffindor and Slytherin) is not featured in the movie, as it is meant to take place several weeks after the delivery of the Firebolt.

As with the series' previous instalments, Prisoner of Azkaban was a large merchandising opportunity.[29] The video game version, designed by EA UK, was released 25 May 2004 in North America and 29 May 2004 in Europe. Mattel released film tie-ins that included the Harry Potter Championship Quidditch board game and character action figures.[30]Lego also expanded on its previous merchandising for the first two films with the release of sets ranging from the Knight Bus to the Shrieking Shack.[31]

Harry Potter and the Prisoner of Azkaban held its New York premiere at Radio City Music Hall on 23 May 2004,[32] followed by its London premiere at Leicester Square on 30 May 2004.[33] The film then opened in the United Kingdom on 31 May 2004 and on 4 June 2004 in the United States. It was the first film in the series to be released in both conventional and IMAX theatres.[34]

Upon release, the film broke the record for biggest single day in the United Kingdom's box office history making £5.3 million on a Monday.[35] It went on to break records both with and without previews making a stunning £23.9 million including previews[36] and £9.3 million excluding them.[37]The Prisoner of Azkaban currently has the highest-opening weekend at the UK's box office. It went on to make a total of £45.6 million in the UK[38] The film made $93.7 million during its opening weekend in the United States and Canada at 3,855 theatres, achieving, at the time, the third biggest-opening weekend of all time.[39] This opening also broke Hulk '​s record ($62.1 million) for the highest-opening weekend for a film released in June.[39]The Prisoner of Azkaban held this record for five years until Transformers: Revenge of the Fallen topped it in 2009 with $108.9 million.[40] The film was also No. 1 at the North American box office for two consecutive weekends.[41]

The Prisoner of Azkaban made a total of $796.6 million worldwide,[1] which made it 2004's second-highest-grossing film worldwide behind Shrek 2.[42] In the US and Canada, it was only the year's sixth-highest-grossing film, making $249.5 million.[43] Everywhere else in the world, however, it was the year's number one film, making $547 million compared to Shrek 2's $478.6 million.[44] Despite its successful box office run, Azkaban is currently the lowest-grossing Harry Potter film (all the other Harry Potter films have grossed more than US$875 million worldwide). Still, Harry Potter and the Prisoner of Azkaban is currently the 45th-highest-grossing film of all time.

Prisoner of Azkaban earned notable critical acclaim, garnering a 91% "Certified Fresh" approval rating at the review aggregator Rotten Tomatoes with a consensus stating,"Under the assured direction of Alfonso Cuaron, Harry Potter and the Prisoner of Azkaban triumphantly strikes a delicate balance between technical wizardry and complex storytelling."[45] The film also received a score of 82 out of 100 at Metacritic, which signifies "universal acclaim."[46]

Mick LaSalle of the San Francisco Chronicle lauded the film's more mature tone and said it was "darker, more complex, rooted in character."[47]The Hollywood Reporter called the film "a deeper, darker, visually arresting and more emotionally satisfying adaptation of the J.K. Rowling literary phenomenon," especially compared to the first two installments.[48]Peter Travers of Rolling Stone gave the film three-and-a-half out of four stars: "Not only is this dazzler by far the best and most thrilling of the three Harry Potter movies to date, it's a film that can stand on its own even if you never heard of author J.K. Rowling and her young wizard hero."[49] Stephanie Zacharek of Salon.com asserts it to be "one of the greatest fantasy films of all time."[50] Nicole Arthur of The Washington Post praised the film as "complex, frightening, [and] nuanced."[51]Roger Ebert gave the film three-and-a-half out of four stars, saying that the film was not quite as good as the first two, but still called it "delightful, amusing and sophisticated"[52] Claudia Puig from USA Today found the film to be "a visual delight," and added that "Cuaron is not afraid to make a darker film and tackle painful emotions."[53] while Richard Roeper called the film "a creative triumph."[54] Sean Smith from Newsweek said: "The Prisoner of Azkaban boasts a brand-new director and a bold new vision," he also called the film "moving," praising the performances by Radcliffe and Watson,[55] while Entertainment Weekly praised the film for being more mature than its predecessors.[56]

The film also ranks at No. 471 in Empire magazine's 2008 list of the 500 greatest movies of all time.[58]IGN designated Prisoner of Azkaban as the fifth best fantasy film.[59] Additionally, Moviefone designated the film as the tenth best of the decade. In 2011, the film was voted Film of the Decade at the First Light Awards by children aged 5–15.[60]